1. Field of the Invention
The present invention relates generally to controlling of vibrations generated in a portable terminal, and more particularly, to a method and apparatus for generating vibrations to cause a user to feel a sense of direction on a portable terminal.
2. Description of the Related Art
Portable terminals include, for example, mobile communication terminals such as cellular phones, Personal Digital Assistants (PDAs), portable Digital Multimedia Broadcasting (DMB) terminals, MP3 (MPEG layer-3) players, Portable Multimedia Players (PMPs), and portable game players such as PlayStation Portable (PSP) systems. Initially, portable terminals provided unique functions in the early stages of development, but gradually they have been developed to provide multiple functions. Namely, a single portable terminal may offer a mobile communication function, game functions, a multimedia play functions, and the like.
Typically, portable terminal is equipped with a vibrator which provides vibration for transmitting information to a user according to an operation control of the terminal. For example, vibration may be used to inform a user of an incoming call or message or may be used to inform a user of a specific event regarding games being played on the terminal. When using the portable terminal in public places, vibration may be frequently used instead of sounds as a means for preventing interruptions due to the occurrence of noise.
The use of vibration instead of specific sound effects is effective in that the occurrence of noise is prevented and, on the other hand, during the playing of games the player experiences a sense of reality because the player can directly feel the physical vibration. Accordingly, not only a portable terminal but also a game pad or a game controller can be equipped with the vibrator so as to generate proper vibration according while the games are in progress.
A game pad or game controller tends to basically provide haptic feedback in order to increase the player's sense of reality. In this case, a method for controlling vibration so that a user can feel a sense of direction in addition to simple vibration has been proposed.
Generally, two or more vibrators are used to achieve a sense of direction and motion of vibration. Especially, since an existing game pad or game controller is used by a user by holding it in both hands, vibrators are arranged at positions separated by a sufficient distance irrespective of their types and the driving time and strength of the vibration are controlled, thereby achieving the sense of direction and motion.
For example, when Eccentric Rotary Motors (ERMs) are used as vibrators, several methods have been proposed, including a method for achieving various two-dimensional directions by varying phases of two motors while the motors rotate, a method for generating a sense of direction by varying duty cycles of the two motors and driving the motors using different strengths, and a method for achieving a sense of two-dimensional direction by controlling the strength of vibration of an x-axis vibrator and a y-axis vibrator.
Attempts have made to apply the above-described vibration generation methods to a portable terminal. This is because, as the portable terminal has included multimedia functions and personal computer functions, haptic feedback is applied to structures such as a touch screen to achieve a sense of click, and various methods have attempted to increase the sense of reality and pleasure in games and services.
However, since portable terminals are generally small sized and are hand-held, and since there is an increasing demand for a relatively large screen size in a simple and slim design, the portable terminal generally has a size smaller than the game pad or game controller. Thus, it is difficult to mount two vibrators in a portable terminal because it is generally not possible to ensure a sufficient distance between the two vibrators so as to generate a sense of direction and motion of vibration.
Moreover, portable terminals usually are constructed to act like one rigid body because the outer case is made of rigid plastic or metal material and the interior has a compact structure without gaps due to the slim design. Hence, a vibrator vibrates the entire portable terminal and thus it is difficult for a user to feel a sense of direction of vibration.